Protect it in your browser
- Open Protect PDF and drop in your PDF.
- Type a password twice.
- Click Protect PDF and download it.
The PDF is encrypted with AES-256 on your device. Neither the document nor the password is uploaded.
Choose a strong password
Encryption is only as strong as the password. Use at least 12 characters, or four random words. A password generator makes one for you.
Send the password separately
Do not put the password in the same email as the PDF. Send it by text message, say it on the phone, or agree on it in advance, so someone who gets hold of the email does not get both.
On a Mac with Preview
Open the PDF in Preview, choose File → Export, tick Encrypt (called Permissions in some versions) and set a password.
If you forget the password
There is no way to recover it: that is the point of encryption. Keep the original unprotected file somewhere safe, or store the password in a password manager.